This invention relates to treatment of diseases of the bladder and urinary tract. More specifically, the invention is directed to a method of delivering medicinal compositions directly to the bladder at controlled rates.
Various modes for delivery of medicinals to the bladder and urinary tract are known in the art. Patients with cancer may, for example, be treated with chemotherapy, i.e., toxic agents which primarily destroy malignant cells. The drugs are normally administered as injections, but in the case of carcinoma of the urinary bladder, instillation of an anticancer or cystostatic agent directly into the cavity of the bladder is recommended. This is done by daily injections of the drug through a catheter which is introduced through the urethra.
The advantage of this focal treatment is that the drug is placed in direct contact with the malignant cells, whereas the drug concentration everywhere else in the body is minimal. This reduces the occurrence of general side effects. Although this principle holds true for any focal application of a drug, it is particularly pertinent when it comes to administration of drugs directly into the cavity of the bladder, because the permeability of compounds through the mucosal lining of the bladder is low.
The drawbacks of this type of focal treatment are that the patient must undergo daily catheterization of the bladder which is both costly and unpleasant and the treatment is inefficient because the drug stays in the bladder for only a few hours, i.e., until the next micturition or urination.
Another means of administering medicinals to the bladder and urinary tract is to take the medicinals orally. In such a case, the medicinals gradually pass from the kidney into the bladder. Antibiotics, e.g., sulphur drugs, or urinary tract antiseptics and anesthetics, e.g. pyridium, are administered in this manner. Uncertain drug levels may be obtained in this manner due to various rates of individual clearance of the medicinals through the kidneys. In the case of anesthetics, a significant period of time may pass before any relief from pain or discomfort is achieved.
The search has continued for new and improved methods of delivering drugs to the bladder and delivery devices used in those methods. This invention was made as a result of that search.